Full area safety valve



13mm R, A. K. soRENsEN ZJMQE FULL AREA SAFETY YVALVE Filed July 3l, 19292 Sheets-Sheet l Mm w' A. K. SORENSEN 2,043,203

FIULL AREA SAFETY VALVE Patented June 2, 13936n ENT AOFFICE FULL AREASAFETY VALVE Alfred K. Sorensen, Chicago, Ill.. assignor to Crane Co.,Chicago, Ill., a corporation of Illinois Application July 31, 1929,Serial No. 382,298

4 Claims.

This invention relates to an improved safety valve of thepilot-controlled type.

Among other objects, the invention is intended to provide a practicableand eilicient safety -valve p which will give a full area discharge, i.e. a discharge of cross sectional area equivalent to the full area ofthe opening in the valve seat, and which will operate with substantiallythe same certainty and precision as a standard pop safety valve.

A furtherobject is to provide a practicable, eicient and reliable safetyvalve of large discharge capacity for use as an emergency relief valvein connection with a high pressure steam boiler of large capacity, .orfor the purpose of providing adequate relief capacity for any pressuresystem of large capacity.

The invention is practically adapted for embodiment in valves ofunlimited large sizes and discharge capacities. Such a valve may be usedin place of a gang of ordinary safety valves to provide adequate reliefcapacity to Yprotect the boilers of a power plant from suddenaccumulation of an enormous surplus of steam at high pressure in eventof accident or emergency causingsudden release of the power fromthe'load or the `shutting oi ofthe power from the machinery `operatedthereby.

An illustrated embodiment of the invention is shown in the accompanyingdrawings `in which: "i Fig. l isa vertical section through the center 0i=a complete -valve constructed in accordance with ythis invention,

Fig. 2 is a vertical section .through the lower portionof a valve takenon a plane perpendicular to Vthat of Fig. 1, and

Fig. 3 is a section partially in section taken'onV the line `3--3 o-fFig..2.,

In the illustrated embodiment of this invention the valve properconsists of a body indicated generally by reference numeral I having aside inlet 2, an outlet 3 and a cylindrical portion vil the lower end ofwhich is flanged as at .-6 and closed by a cap `IV secured thereto bymeans of bolts 8. Theinlet 2 and outlet 3 may also .be flanged asillustrated to receive suitable complementary connecting fittings. 'Iheoutlet orifice is threaded -to receive a seat member 9 adapted to `beengaged and closed by the seating ring Il) threadedly secured to thehead-end II of .a piston-.like main valve the skirt portiongIZ `of whichisttedwith sealing rings I3 bearing against a sleeve 'I4 fitted withinthe cylindrical portion VIl and abutting against `shoulder I6 to formatight cylinder within the cylindrical portion '4 .of the valve body I.yThe length of the skirt portion I2 and the cylindrical portion 4 of thebody of the valve are so proportioned vthat the piston valve is capableof sufficient reciprocatory motion to 5 give a full opening of the valveseat 9. The'lower portion or valve body I is 'formed with an annularrecess Il providing a chamber between the sleeve It and the .body I. Thelower end of sleeve 'I4 is provided with openings I8 establishingcommunication between chamber Il and the 'interior of the. piston valve.The upper end of the piston valve is reduced in diameter as at 2l toprovide a concaved outer vsurface 22 creating an `annular chamber 2 3between the reduced end of the pis- 15- ton and the inner wall of thecylindrical portion 4 of body I whichchamber is in direct communicationwith the inlet 2.

Connected to the `inlet 2 is a by-pass connec- 20 tion 23 leading to athrottle valve 26 of lstandard construction having, however, a cap 2lthereon to prevent unauthorized adjustment of the valve. The outlet ofthe throttle valve ,connects with chamber 'l'i by means of pipe `28,thus connecting 2- inlet 2 with the interior of the piston valve throughopenings I8. It is apparent that the inlet is in communication with thevconcaved surface22 of the piston valve as well as the interior ofthepiston valve. 30

The chamber Il is also provided with ,a connection 23 leading toapilotsafety valve 3|. The pressure in chamber il and the region I9 of theinterior of the piston valve is thus controlled by means of therelatively small pilot vvalve 3l which, 35 by controlling the pressureagainst the interior ofv the valve, controls the action of the mainvalve. This pilot valve maybe of any standard construction capable ofgiving a specific quantity of discharge with a suitable blow-back.

In order to give an unrestricteddischarge, a duplex discharge connectionis secured to the flange of the outlet 3 by means of a complementaryange132 and'bolts'33. VThe discharge connection in the illustratedembodiment is in the form oa Y, but may be in any convenient form tosuit the installation, the stem 34 ,thereof terminating .in flange 32and the outlets 36 and 31 extending upwardly andconstituting duplexdischarge yopenings giving a substantially unrestricted dischargepassage from the voutlet end of the main valve to the atmosphere. As anadditional guiding means for the main valve in its reciprocating.movements there is provided a .valve rodvsecured at one endtothe headof the valve and projecting through a bushing 39 secured in a web 4|which joins the upper ends of the outlets of the Y. To normally keep thevalve in a closed position against the action of gravity, a compressionspring 42 surrounds rod 38 and is placed under compression between theouter surface of web 4| and a spring cap 43 threadedly engaging rod 38and locked into adjusted position by means of nut 44. In order tocushion the movements of the valve there is provided the usual dashpotmechanism 45, which mechanism however need not necessarily be providedfor the efficient operation of the valve. The dash 48 is carried uponthe outer end of rod 3a and ts within Va dashpot chamber 49. Theremainder of the dashpot construction is well known `and need not befurther described. The cap 'l is provided with the usual drainageconnection 5| with the customary valve (not shown).

In operation the inlet 2 is connected to the apparatus to be controlledby the valve. The fluid from the apparatus enters the inlet 2 andchamber 23 and acts upon surface 22. At the same time iluid passesthrough connection 24 and throttle valve 25, and enters the chamber Il,passing through openings I8 into the chamber i9 of the piston valveacting upon the inner surface of the head I and tending to positivelyclose the piston valve upon the seat 9. The interior f of the pistonvalve and chamber is also open to the pilot valve connection 29 and thepilot valve 3|.

After the pressure, for which pilot 3| is set, is reached, the pilotvalve 3| will open and therei by reduce the pressure in chamber Il andthe interior I9 of the main valve, thus u-nbalancing the piston valveand permitting the pressure in the supply line which still acts uponsurface 22 to open the main valve. In View of the fact that the pressuretending to close the Valve is substantially reduced, the piston valvewill open to its full extent, thus giving a full area opening andpermitting the excess pressure to pass olf unrestricted. From the outletend of the main valve the fluid passes upwardly through both branches 36and 3'| into the atmosphere. After the pressure has been reduced to thepredetermined value the pilot valve 3| will close and allow the pressureto build up in chamber and the interior I9 of the main valve, thuspositively overbalancing the pressure against the relatively smallerexterior surface 22 of the main valve and positively closing the valve.The action of the main valve may be controlled and regulated withincertain limits by means of the dashpot 40 in the customary manner.

The throttle valve 26 may be regulated to control the flow of fluidthrough the by-pass and thereby control the time period necessary tobuild up pressure in chamber and the interior |9 of the main valve. Inthis manner the closing of the main valve ,may be closely regulated tosuit any desired and particular conditions. By means of the dashpot andthe throttle valve, the lift and blowback of the entire valve assemblymay be adjusted and regulated within close limits to substantially anydesired conditions.

It is also pointed out that a valve of the type illustrated has a fullarea opening, the area of said opening being of the area of the seatopening, whereas in valves of ordinary construction the lift rarelyexceeds 10% of the diameter and only in exceptional cases reaches 25% ofthe diameter. It is believed to be apparent, therefore, that there isprovided a full area opening valve which is capable of dischargingrelatively large quantities of iluid in a relatively short period oftime and which may be adjusted and controlled to suit many and variousconditions.

It is obvious that many changes may be made in the details ofconstruction of the embodiment of this invention which is given forillustrative purposes only without departing from the spirit and scopeof the invention as defined in the appended claims.

I claim:

l. A safety valve comprising a body having an inlet and an outletthereto and being further provided with a Valve cylinder therein, avalve seat between said cylinder and said outlet, a hollow diif-erentialpiston valve mounted for reciprocating movement in said cylinder andhaving a seating end adapted to engage and close said valve seat, saidpiston valve being further provided with a reduced portion adjacent itsseating end and forming a chamber between the piston and the cylinderwall upon the inlet side of said seat, said chamber being incommunication with said inlet, a by-pass from said inlet to the interiorof said piston valve subjecting the interior thereof to the inletpressure, the interior piston area subject tothe inlet pressure beinggreater than the exterior piston area subject to the inlet pressure, anexhaust passage in communication with the interior of said piston valve,

and a normally closed pilot safety valve in said exhaust passage subjectto the pressure therein and operable to open at a predetermined upperlimit of said pressure and to close upon reduction of said pressure to apredetermined lower limit, said exhaust passage discharging to theatmosphere independently of the exhaust through said body, whereby th-eaction of said pilot safety valve is uninuenced by the pressure in theoutlet of said body, said pilot valve being disassociated fro-m saidby-pass and controlling only the exhaust passage to the atmosphere,there being constant communication through said by-pass between saidinlet and the interior of the piston valve.

2. A safety valve comprising a cylinder, a differential piston valvetherein, an inlet passage for connection with a source of fluid underpressure communicating with said cylinder through a lateral opening oflarge area adjacent to one end of the cylinder, said cylinder having insaid end an outlet opening of large area and a surrounding valve seat onwhich the piston valve seats, the other end of the cylinder beingclosed, the proportions of the parts being such as to permit asuiiicient movement of said piston valve from its seat to provide alarge area discharge capacity, said piston valve being formed to providewhen closed an effective front piston area exposed to the pressure insaid inlet passage, which effective front area is less than theeffective rear piston area, a relatively restricted by-pass passageconstantly establishing communication between said inlet passage and theinterior of the cylinder at the rear side o-f the piston valve, wherebysaid piston valve is normally held closed by the pressure action on itsrear side, and means controlled by the pressure behind the piston valvefor effecting when said pressure reaches a predetermined limit a rapidrelease thereof suilciently to cause the full opening of said pistonvalve by the pressure action on its front area and for discontinuing thepressure-releasing action when said pressure behind the piston valvefalls to a predetermined limit below that at which said piston valveopens, said means comprising an exhaust passage in communication withthe closed end of the cylinder and a normally closed pilot safety valveof determined discharge capacity and blow-off controlling saidexhaustpassage and controlled by said pressure behind the piston Valveto open at said predetermined upper pressure limit and to close at saidpredetermined lower pressure limit for reestablishing the con- 'ditionfor creating sufficient pressure behind the piston valve to close it,whereby said piston Valve is controlled by the pilot valve toopen inresponse to a predetermined inlet pressure and to close in response to apredetermined reduction of such pressure.

3. A safety valve comprising a cylinder, a pressure differential pistonvalve therein, an inlet passage for connection with a source of fluidunder pressure communicating with said cylinder through a lateralopening of large area adjacent to one end of the cylindensaid cylinderhaving in said end an outlet opening of large area and a surroundingvalve seat on which the piston valve seats, the other end of thecylinder being closed, the proportions of the parts being such as topermit a suicient movement of said piston valve from its seat to providea large area discharge capacity, said piston valve being soshaped as toprovide when closed a pressure chamber between it and the outlet .end ofthe cylinder in communication with said inlet passage, whereby thepiston valve when closed is subjected to pressure acting in a directionto open it upon an effective piston area substantially less than thefull piston area, means comprising a by-pass having an adjustable orcecontrol establishing communication through a relatively restrictedpassage between said inlet passage and closed end of the cylinder,whereby the piston valve is subjected to a pressure on its full area ina direction to hold it closed, an exhaust passage independent of controlby said orifice control in communication with the closed end of thecylinder, and a normally closed pilot safety valve in said exhaustpassage subject to the pressure therein and operable to open at apredetermined upper limit of said pressure and to close upon reductionof said pressure to a predetermined lower limit below that at which themain piston valve will open, said by-pass passage being independent ofcontrol by said pilot Valve, whereby said piston valve is controlled bythe pilot valve to open in response to a predetermined inlet pressureand to close in response to a predetermined reduction of said pressure.

4. A safety valve comprising a cylinder, a pressure dilerential pistonValve therein, an inlet passage for connection with a source of fluidunder pressure communicating with said cylinder through a lateralopening of large area adjacent to one end of the cylinder, said cylinderhaving in said end an outlet opening of large area and a surroundingvalve seat on which the piston valve seats, the other end of thecylinder being closed, the proportions of the parts being such as topermit a sufcient movement of said piston valve from its seat to providea full area discharge capacity, said piston valve being so shaped as toprovide when closed a pressure chamber between it and the outlet end ofthe cylinder in communication with said inlet passage, whereby thepiston valve when closed is subjected to pressure acting in a directionto open it upon an effective piston area substantially less than thefull piston area, means comprising a bypass having an adjustable oricecontrol establishing communication through a relatively restrictedpassage between said inlet passage and closed end of the cylinder,whereby the piston valve is subjected to a pressure on its full area ina direction to hold it closed, an exhaust passage independent of controlby said orice control in communication with the closed end of thecylinder, and a normally closed pilot valve in said eX- haust passagesubject to the pressure therein and. operable to open at a predeterminedupper limit of said pressure and to close upon reduction of saidpressure to a predetermined lower limit below that at which the mainpiston valve Will open, said by-pass passage being independent ofcontrol by said pilot valve, whereby said piston valve is controlled bythe pilot valve to open in response to a predetermined inlet pressureand to close in response to a predetermined reduction of said pressure.

ALFRED K. SORENSEN.

